-Castle been a center of turbulent storm-

Overview

Brief History

Shiroi castle (白井城) is located at the edge of V shaped height at the merging point of Tone-gawa river and Agatsuma-gawa river little apart from central area of Shibukawa city. Castle site is exactly a northwestern end of Kanto plain and a narrow flat area being surrounded by Haruna mountain and Akagi mountain, two of three large mountains of Kozuke province (Gunma prefecture).Tone-gawa river and Agatsuma-gawa river form Shiroi castle have been used as communication route from Kozuke province to Echigo province (Niigata prefecture) and north part of Shinano province (Nagano prefecture). Even today every transportation including Shinkansen train and highway pass this narrow area, Because of this geographic condition, Shiroi castle was not only tactically secure but also strategically important castle of the area.

Origin of Shiroi castle and ancient regime of Kanto region

Precise year is unknown but Shiroi castle might be built by Shiroi-Nagao clan in 15th century. Shiroi-Nagao clan was a tributary of Nagao clan, the house served to Uesugi clan which was a high class retainer of Muromachi Shogunate and served the role of "Kanto-Kanrei", the general minister of Kanto region long time. Nagao clan at Echigo province which turned out Kenshin Uesugi (1530-1578) was a same family.Ashikaga clan which established Muromachi Shogunate was originally a local retainer of Kamakura Shogunate at Ashikaga area, at the border of current Tochigi prefecture and Gunma prefecture. But in 1333, Takauji Ashikaga (1305-1358), the leader of Ashikaga clan, supported anti-Shogunate movement of Emperor Godaigo (1288-1339) and ruined Kamakura Shogunate. After the conflict against the Emperor after that, Takauji formed Muromachi Shogunate at Kyoto city.After the establishment of Shogunate, Kanto area continuously has been an important area as native place. To govern Kanto region, Muromachi Shogunate placed their relative as "Kamakura Kubo" (the highness at Kamakura). But also there was a fear that this Kamakura Kubo attempts independence at distant area, thus Shogunate also sent Kanto-Kanrei as a council and watchdog. Except for its beginning, Uesugi clan hereditary served Kanto-Kanrei.

Mutual attack of two authorites

But this two-head structure had a substantive risk of collapse. In 1416, Zenshu Uesugi (?-1417), former Kanto-Kanrei but dismissed by Kamakura-Kubo Mochiuji Ashikaga (1398-1439), rebelled to Mochiuji and once expelled him from Kamakura city. But next year Zenshu was subjugated by Shogunate army and killed himself.However, next time, Mochiuji became hostile to Shogunate. Mochiuji hoped to be the sixth Shogun but could not, thus became opponent of Yoshinori Ashikaga (1394-1441), an authoritarian new Shogun. In 1539, Mochiuji expelled Norizane Uesugi (1410-1466), the Kanto-Kanrei who tried to coordinate Mochiuji and Shogunate, then Yoshinori seemed this as a rebel then ordered surrounding local lords to attack Mochiuji. Mochiuji lost the battle also killed himself.

Division of Kanto region by Koga-Kubo and Uesugi clan

Kanto region once stabilized, then Muromachi Shogunate appointed Shigeuji Ashikaga (1434-1497), a survived son of Mochiuji, to restore the traditional order. But Shigeuji had a hostile view to Uesugi clan once beat Mochiuji, then in 1454 Shigeuji killed Noritada Uesugi (1438-1455, son of Norizane Uesugi and served Kanto-Kanrei, and started long battle against Uesugi clan. At first Shigeuji Ashikaga broke Uesugi army, but being attacked strong lord ordered by Shogunate, Shigeuji crossed Tone-gawa river and placed at Koga castle then named as Koga-Kubo (Koga highness). Uesugi clan and Koga-Kubo divided Kanto region into west and east by Tone-gawa river, and faced each other. Among Uesugi clan, Yamanouchi-Uesugi clan, the main family of the clan, protected north half of Kanto region, and let Ogigayatsu-Uesugi clan guard south half.Furthermore, Muromachi Shogunate looked at this conflict newly sent their relative Masatomo Ashikaga (1435-1491) to unite them, but facing the antipathy of local lord and had to stay at Izu province (Izu peninsula) before Kanto region. As such, a stalemate situation of Kanto region continued over 20 years.

Rebel of ambitious general

But behind this non-moving status, next era was quietly approaching. During the long conflict upper authority such as Kanto-Kubo or Uesugi clan lost authority and human resource, and retainers experienced and survived severe battles steadily grew their power. Furthermore, the battle of Onin occurred at Kyoto city involving Muromachi Shogunate and major governors in 1467, and Shogunate lost is authority and compelling power to Kanto region Under this circumstance, two brilliant generals emerged into the stage. One of Dokan Ota (1432-1486), the chancellor of Ogigayatsu-Uesugi clan who was known to build current Edo castle for the first time. Another of Kageharu Nagao (1443-1514), who was the leader of Shiroi-Nagao clan which was the house of chancellor of Yamanouchi-Uesugi clan and the lord of Shiroi castle. Kageharu activated at the battle against Koga-Kubo under Yamanouchi-Uesugi clan, but being feared his talent and was not approved to succeed the position of chancellor.In 1475, Kageharu gathered surrounding local lord and rebelled against his master Yamanouchi-Uesugi clan at Hachigata castle (Saitama prefecture). At first Kageharu asked Dokan Ota who was a distant relative to raise a army together but was refused. Kageharu independently assaulted the army of both Uesugi clan faced Koga-Kubo army at Iroko area and broke them. Looking at this other local lords supported Kageharu, and the traditional order of Kanto region seemed to collapse.

Struggle of two talented generals and afterward

But Dokan Ota firmly supported Ogigayatsu-Uesugi clan before the attack of Kageharu, both for Uesugi clan and himself. Dokan firmly kept the line of Edo castle, Iwatsuki castle and Kawagoe castle as a strategic area, and separately broke the local lords belonged to Kageharu by brilliant maneuver. Furthermore, as Kageharu was supported by Koga-Kubo as the enemy of the enemy, thus Dokan urged his master to coordinate with Koga-Kubo.In response to the steady strategy of Dokan, Kageharu boldly attacked Dokan but was not successful. Because of the attack of Dokan, Kageharu lost supporting lords and retreated to the mountainous Chichibu area and kept resistance, but finally surrendered in 1480. This time Shiroi castle was also captured by Yamanouchi Uesugi clan. Ancient regime of Kanto region seemed to survive this turbulence.But during this campaign, Ogigayatsu-Uesugi clan increased their power by activation of Dokan and was not retainer of Yamanouchi-Uesugi clan any more. Furthermore, the talent and power of Dokan became a fear for his master Ogigayatsu-Uesugi clan. In 1486, Dokan Ota was assassinated by his master Sadamasa Uesugi (1443-1494), then Ogigayatsu-Uesugi clan and Yamanouchi-Uesugi clan rushed into total war.

Arrival of new power

Both Uesugi clan fought for over 50 years including several interruptions. Kageharu Nagao continuously fought against Yamanouchi-Uesugi clan in this battle and once recovered Shiroi castle, but finally was broken and died in wander. Utilizing this battle of two Uesugi clans, Hojo clan which captured Izu province in 1493 gradually expanded their territory depriving from Ogigayatsu-Uesugi clan. In 1546, Ogigayatsu-Uesugi clan lost the major part of its territory allied with Yamanouchi Uesugi clan and attacked Kawagoe castle occupied by Hojo clan. But because of the desperate night attack of Hojo clan, careless Uesugi army suffered severe defeat and the leader of Ogigayatsu-Uesugi clan died in the battle. Now Hojo clan became the ruler of Kanto region instead of Uesugi clan.Hojo clan next attacked Yamanouchi-Uesugi clan, and fell its main base Hirai castle in 1553. Norimasa Uesugi (1523-1579) escaped to Echigo province which was held by Kagetora Nagao (1530-1578) who was praised as the god of war. Norimasa gave Kagetora the name of Uesugi and position of Kanto-Kanrei,. then Kagetora renamed to Kenshin Uesugi. Kenshin had a justification seek the chance intrude Kanto region to break Hojo clan and restore the traditional authority.

Stopping point of expeditions

In 1561, Kenshin at last started his campaign against Kanto region. Kenshin gathered many local lords once belonged to Hojo clan, and swept over Kanto region. Kenshin once captured major part of Kanto region and encircled Odawara castle, the main base of Hojo clan. but because of the lack of supply Kenshin had to give up it. Kenshin placed his side retainers at important castles and once returned to Echigo province.But looking at the return of Kenshin, Hojo clan started to recover lost territory. As Kenshin was at distant place and had to face with Takeda clan, the warlord of Kai province (Yamanashi prefecture) and ally of Hojo clan at the same time, Hojo army gradually pushed up its front toward north. In response to this, Kenshin made over 10 times expeditions from Echigo province and fought with Hojo side lords. As Shiroi-Nagao clan has same ancestor of Kenshin, they cooperated with Kenshin in spite of inferior situation. Shiroi castle was a suitable connecting point from Echigo province into Kanto plain. Kenshin frequently used Shiroi castle as a strategic point.

Structure of Shiroi castle

Having good natural condition, the structure of Shiroi castle was simple. The V shaped edge of the height is horizontally separated into three areas by dry moats. Central area of the castle is located at the tip of height, has a triangle shape of 150 meter long. At the middle part of its north line there is a masugata style combined gate decorated by stone wall, might be built around 1600. The north line of central area faces secondary area is protected by tall clay wall and deep dry moat.Secondary area locates at the north of central area which is 200 meter wide and 50 meter long, and third area is ahead of secondary area whose size is about 300 meter wide and 100 meter long. These areas were formerly protected by clay walls but most part was lost by cultivation. As east line of the castle is a cliff but not a river, this line is also secured by dry moat of over 10 meter wide with corridor area.Outside of these core areas, from north to east, there was an outer barrier whose total length is over 2 kilometer. The vast space between outer barrier and core area might be used as a castle town, and also utilized as a camping and storage space at expedition by Kenshin.

End of turbulent era and Shiroi castle

After the death of Kenshin, Uesugi clan lost its territory at Kanto region. Once Shiroi castle belonged to Takeda clan, but after the fall of Takeda clan in 1582, Hojo clan captured whole Kozuke province including Shiroi castle. It was an ardent wish of Hojo clan over 30 years, but did not stay long. In 1590, central ruler Hideyoshi Toyotomi (1537-1598) subjugated Hojo clan by overwhelming army and Hojo clan ended its history of 100 years and five generations. This was also an end of turbulent era of Kanto region continued over 100 years. At this campaign Shiroi castle fought against Hojo clan then opened, thus Shiroi castle recorded its name both at beginning and end of this turbulent period. After the fall of Hojo clan, Ieyasu Tokugawa (1543-1616) was appointed as a lord of Kanto region under Toyotomi government. Yasushige Honda (1554-1611), an important retainer of Ieyasu who later served as a commander of Okazaki castle (Aichi prefecture), the birthplace of Ieyasu, was appointed as a lord of Shiroi castle. Yasushige reformed Shiroi castle into a modern one equipped stone walls, and also developed castle town spreads at east of the castle. Shiroi castle had been used under Tokugawa government nearly 30 years, but abolished in 1623.

Afterward of castle

Now all building was lost but structure of central area including massive clay wall and dry moat remains on the height. Structure of other parts are mainly lost but keep slight mark, and Shiroi posting town continued after the abolishment of castle still keeps traditional atmosphere with several old houses at the next of castle. Large size flat area and powerful structure of central area clearly shows Shiroi castle had been an center of turbulent period of Kanto region.